Most easily done through synastry. A professional would do it this way:
Outside of chart rectification, synastry is the most time consuming of astrology work. *If you were to have a profesisonal astrologer do this for you it would involve a number of steps:
1. a small analysis of both charts
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2. an analysis of both charts for determining suitability for *a sustained relationship
3. determining the strength and harmony/disharmony of the planets in each chart with an emphasis ob disharmonious ones since nobody ever went to a marriage counselor to complain they were having too much fun in their relationship
4. determining the strength and disharmony of the houses in both charts.
5. Finding where the most disharmonious planets on one chart are in the most disharmonious houses in another chart: *for both charts
6. Finding the most disharmonious planets in each chart aspecting the most disharmonious planets in the other chart for both charts, and what the aspect is
7. Finding where Dark Moon Lilith aspects the most harmonious planets in each chart.